Read a little closer — and saw the word “never”. I am assuming you are talking about either a life or death situation like an AED or a fully automated situation. If there is any human contact you need to think about usability when it is task oriented and do not care about stickiness in that case. For a fully automated solution — the tech should be so good the user doesn’t need to engage and hence the stickiness is how good the tech is — that it just works is sticky enough. Hope both responses help!